Gradient Map Alpha
gradient-map-alpha
The gradient-map-alpha parameter mixes the gradient-map result back with the original image. It accepts a value from 0 to 100 and defaults to 100.
At 100 the output is the gradient map alone. At 0 the original image is returned untouched. Values in between keep some of the original color, which is the usual way to tint a photograph rather than fully recolor it.
